This is an open-, nonrandomized, rising-dose, continuous infusion study in patients with solid malignancies which will test the hypothesis that administration of L-778123 for 5 weeks in combination with radiotherapy at a dose that achieves steady-state plasma concentrations of at least 2.0 uM will be generally safe and well tolerated in patients with solid malignancies. The primary objective is to evaluate the safety and tolerability of L-778123, including determination of the maximally tolerated dose, when administered for weeks 1, 2, 4, 5, and 7 of radiotherapy for pancreatic cancer. Patients will be treated with continuous infusions of L-778123 while simultaneously receiving standard radiotherapy on weeks 1,2,4,5, and 7 until the maximally tolerated dose is defined or until a maximum dose of 560 mg/m2/day has been achieved. Patients will be stratified into 2 strata: (1) pancreatic cancer or (2) head and neck or nonsmall cell lung cancer.